Method of producing retreading matrices



Sept. 14 1926. 1,599,534

M. V.' KERLEY METHOD OF PRODUCING RETREADING MATRICES Filed April '7,1926 W 6 INVENOR.

A TTORNEY.

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METOD @F PRUDUGENG REEREADING MATRIGES.

application filed April 1?,

This invention-relates to a new and proved method of producing matricesfor retreading pneumatic tires and the invention has. tor'its primaryobject to provide a rapid and economical means for the production otmaster patterns, as well as matrices to -ire-establish treads of anydesired design, "whichwill enable the matrices so produced to he readilyinterchangeable and used to equip old and obsolete sectional tire'moldsvwith modern patterns, thus enabling the owner of such molds to maintainmodern and prevalent designs in the retreading oi?- tires.

The invention further aims among its ohjects' toprovide tor theretreadin'g oil the well lmown halloon type of pneumatic tire, byincreasing the thickness of the matrices at one end or each section,thereby to contorm with the diameter oil the tire upon which a new tread"is desired.

Another important object of the invention resides in the loot that a newand un-= used automobile tire may be employed producing duplicate designimpressions to term the initial pattern without injury whatsoever tothettire. 7

With these primary objects in view, the in vention consists further ctlesser objects and advantages, as well, as certain novel features andadvantages residing in the improved application or elements in thecarrying out oi the method and manifested in the following detaildescription, talren in connection rwr with the accompanying drawings,wherein:

Fipanre i represents tire mold and the manner reproducing a treadimpression in the initial or ruhber matrix, prior to the production ofmaster pattern ol mold; laterally talren, illustrating the manner hywhicha lurtherreproduction ot designis ohtained from the rubber matrixto produce a pattern trom which the permanent metal matrix or masterpattern is produced w a Figure 3 represents a fragmentary view or the rhher matrix.

Figured is an end view oil the secondary matrin or pattern,

Figure 5 is sectional view at the sectional me at matrices or masterattern. as produced tor the retreading of be loon tires or tires" atlesser-diameters, and

t represents a vertical cross-section.

19%. serial the. roar.

hit

and established precedent to employ mat-.

rices of both metal and other materials tor the reproductlon of ,desi inrctrcading pneumatic tires, and no novelty resides in the product of thepresent invention aside from the perfect reproduction of design andpermanency of such designs of which the. invention is capable ofattaining, the-nov-- eltyresiding only in the improved manner hy whichthe matrices are produced. Now, in proceeding further, attention isdirected to Figure l of the drawings, in which the character 1 denotes asectional metal tire mold of any suitable constructroawhich is equippedwith an auxiliary heating arrangement consisting preferably of gashurners 2, curved to contorm as shown with'the semi-circular body of themold and to which reference will again hereinafter be made. Theseburners are provided with a suitable gasconnection 3. in addition tothis heating arrangement, a steam chaher d is provided in the mold,having a connection 5.,

Suitable clamping means ti tor the tire is further provided on the mold,however this element may he altered in any manner to suit the-occasion.The mold is mountedchannel or the mold a sheet of rawirubher or itsequivalent or? proper width, length and thickness, alter whichapneumatic auto mobile tire 8, or size to lit the mold is placed upon therubber sheet, and sand or air hag or the usual construction is placedwithin the tire, after which the latter is clamped securely in place bythe clamps ti. Steam pressure is then applied to theoritent outapproximately torty or dirty pounds and through the heat thereof theruhher sheet attains a semieplastic state to readily receive-theimpressions of the design on the surface of the tire. The completedmatrix thereloy produced is shown in Figure 3, and referred to hy'thecharacter 9, however, as previously stated, is not claimed herein asnovel. 4 I v New, in converting this matrix into one oi metal, or amaster pattern is the novel feature claimed in the invention, therefore,with this in view the rubber matrix is removed from the mold, the edgestrimmed, and the defects, if any, cured then replaced in the mold,Preparatory to producing a secondary matrix from the rubber matrix 9, apair inch of space is. suitably covered with tissue paper or other thinmaterial and cemented to the sides of the metal walls as at .a to retainit in place. A trough is thereby produced in which form the secondarypattern or matrix. Thislatter matrix is prepared initially in a plasticstate from a mixture of water and plaster of Paris, or of molders, sand,litharge and linseed oil. As to the ingredients of this mixturenonovelty is. claimed.

The described mixture is poured between the side walls 10, as in Figure2, the tissue paper at a preventing the mixture from coming in contactwith the walls of the mold and preventing any dificulty' in removing theform 11, also the paper allows'the form to close the space along theedge of the rubber matrix, thus rendering possible a perfect casting ofa metal matrix when the rubber matrix 9 is removed.

Now, having completed the secondary matrix or cope, the latter ispermitted to attain a mechanical set, after which it is removed from themold, and the rubber matrix taken out. The matrix or cope 11 is replacedin the mold and securely clamped to the latter to avoid possibledisplacement, after which molten metal preferably aluminum alloys, orits equivalent is poured into the space intermediate the mold andform,

thus reproducing a perfect duplicate of the rubber matrix in the metaland a master pattern 12, as in Figure 6, is the product from whichdesign reproductions may be made as desired.

As a means for holding the matrix 12 againstmovement in' the mold inretreading a tire, a small hole 13 is drilled in either on thereof andin the mold ends to aline therewith and a short bolt 14 is extendedthrough these holes, as in Figure 1.

A further advantage of the present invention lies in the fact that thetread design of wastes of the tread design may be filled and the tiretread made smooth, after which any desirable tread design may be carvedin the rubber thus -materially simplifying the designing of a new styletrea It is obvious from the foregoing, that the method is built up tofinally produce a matrix which will withstand the intense heat of moltenmetal in the production of the master pattern, and at no time, as insome methods, is the tire, from which the initial design is obtained,subjected to the intense heat of the metal while in a molten state, asthe rubber will not endure such heat, and is wholly inefficient as aninitial pattern in the absence of a secondary or positive cope or matrixformed as described.

Tn Figure" 5, will be seen a modified example of the master pattern,whereby is made possible the retreading of balloon tires, or tireshaving smaller and varied diameters, and which consists of sectionalmatrices 15, produced accordingly to the foregoing method, but in soproducing the initial or rubber matrix 9 is built up at one end in orderto conform with the circumference of the tire from which the design isto be taken, then the tire is placed in the. mold and the describedprocess carried out to finally produce the master pattern 15, which, asobvious from the'Figure 5, has upper ends of greater thickness than thelower end.

Referring again to the heating arrangement 2, it has been found toexpedite the forming of the metal matrix, to first heat the mold 1, to areasonable degree before pouring the metal to insure against prematurecooling which may result in an inferior reproduction of the design.

It should be understood that while all of the operations described asforming the subject matter of the proposed method are included in theannexed claims therefor, certain modifications may be resorted to, suchas substituting other materials for those described, without aflectingthe spirit or intent-of the invention or departing from the scope of thesaid claims.

I claim: 1

1. The hereindescribed method of producing a master pattern tireretreading matrix which consists initially in placing a sheet of rawrubber in a tire mold; then in placing on said rubber sheet; a tirehaving the YOU) desired tread design; then in subjecting said mold to apredetermined steam pressure to reproduce said tread design in saidrubber to produce a matrix; then in removing said tire and'formting sidewalls for said mold; then in filling the trough thereby formed with acomposition-of plaster of Paris to produce a secondary matrix; then inreplacing said secondary matrix in said. mold and securing the same;then in heat ing said mold to a predetermined temperature, and finallyin pouring molten aluminum alloy in the space between said secondarymatrix and mold to produce a mas: ter pattern.

2.- The hereindescribed method of producing a master pattern forretreading tires which consists initially in producing a rubber matrix,by placing a sheet of raw rubher in a tire mold and clamping a tirehavobtain a positive impression from said rubher matrices top-roduceasecondary matrix; then in removing said latter matrix andrubber matrix, and in replacing said secondary matrix; and finally in.pouring molten metal in the space intermediate said secondary matrix andmold to produce a master pattern.

3. The hereindescribed method of producing a master pattern forretreading tires, which consists initially in obtaining a designimpression of a tire by placing a sheet of raw rubber in a mold andclamping the tire thereon, then in subjec'tingthe same to apredetermined pressure, then in removing said tire and rubber matrixthereby formed and curing the defects in the latter and replacing thesame in the mold; then in applying side walls to the mold; then infilling in between said side Walls with a self hardening plasticcomposition to obtain a secondary positive impression from said rubbermatrix to produce a pat tern, then in removing said pattern and rubbermatrix and in replacing said pattern, and finally in pouring moltenmetal in the space between said pattern and mold to produce a masterpattern.

4. The hereindescribed method of re roducinga tire tread design for thepro no time of a master retread matrix which consists initially inplacing a sheet of raw rubher in a mold and clamping a tire thereonhaving the desired tread design; then in subjecting said rubber sheet toa predetermined steam pressure; then in removing said tire and rubbermatrix thereby formed and curing defects in the latter and replacing thesame, then in filling said mold with a self hardening plasticcomposition to 0b-v tain a positive reprint of the design in said rubbermatrix to produce a secondary pattern and rubber matrix and in replacingsaid'secondary pattern, and finally in filling the space between saidsecondary pattern and mold with molten metal to produce a master matrix.

.5. The hereindescribed method of reproducing a tire tread design ininitial matrices for the production of a master pattern which consistsinitially of obtaining an im print of a design in a sheet of raw rubberfrom an unused tire by subjecting the same to steam pressure thereon ina mold; then in removing said tire and rubber matrix tern; then inremoving said secondary patthereby formed from the. mold and curing thedefects in the latter and replacing the same in the mold; then inpouring a self hardening, plastic composition into said mold to obtain asecondary pattern from said rubber matrix; then in removing saidmatrices thereby'formed andreplaoing said secondary matrix in the moldand finally in filling the space between the mold and secondary matrixwith molten metal to produce a master pattern.

In testimony whereof ture.

MELVIE V. KEELEY.

I aflix my signa-

